CONCERTED ANTIBIOTIC EFFECT OF PENICILLIN, METHIONINE, THREONINE AND METHIONINE SULFOXIDE UPON BRUCELLA, EBERTHELLA, SALMONELLA, AND SHIGELLA.

Penicillin susceptibility of highly refractory Gramnegative organisms may be greatly enhanced upon addition of methionine, threonine and methionine sulfoxide. The action of amino acids appears to be synergistic rather than additive. Methionine is essential for the enhancement. Threonine and methionine sulfoxide facilitate the effect of methionine following a reciprocal quantitative relationship.